Microstructure and mechanical properties of Laves phase-reinforced Fe-Zr-Cr alloys

Multi-phase Fe90-xZr10Crx alloys with 0 <= x <= 10 containing cubic C15 and hexagonal C14/C36 Laves phases have been prepared by copper mold casting. The microstructure of the samples consists of micrometer-sized Laves phase particles embedded in an ultrafine eutectic matrix of alternating lamellae of alpha-Fe and Laves phases. Room temperature compression tests of the binary alloy reveal a high strength of 1900 MPa combined with a plastic strain of about 9%. The addition of Cr improves the plastic strain up to 17% while reducing the strength only by about 70 MPa. The increased plastic deformation is linked to the specific structural features of the Laves phases. For the binary alloy, shearing and crack formation within the C15 phase limits plastic deformation. In contrast, in the samples containing Cr no shearing occurs within the C14/C36 phases and crack formation, which is observed at the particle/ferrite interface, is retarded. (C) 2009 Elsevier Ltd. All rights reserved.